Operating valves oe steam-engines



3 Sh t-sn 0. TUFTS. 68,8 eet 3 Steam Engine Valve Gear.

No. 15.025. Patented June 3, 1856.

UNITED STATES OTIS TUFTS,

OF BOSTON,

MASSACHUSETTS.

OPERATING VALVES 0F STEAM-ENGINES.

Specification of Letters Patent To all whom t may concern:

Be it known that I, O'rrs TUFTs, of Boston, Suffolk county,Massachusetts, have invented a new and useful Method of Working theCut-Oft' Valve, Separate or United with the Exhaust-Valve, inSteam-Engines; and I hereby declare that the following description, withthe accompanying drawings, forms a full, clear, and exact specificationthereof.

Figure l is a side view of the steam cylinder with my improvementapplied, one end in section to show the piston, and also the cut-off andexhaust valves united. Fig. 2 is an end View of the same. Figs. 3, 4, 5,6, 7, 8, 9, l0, l1, exhibit the mechanism in detail, to be explained.

I use a thick circular plate (a) placed upon a strong pin (o) projectingfrom the engine frame or bed plate. Said plate receives an oscillatingmotion from an eccentric or its equivalent. That side of the plate whichis nearest the engine frame I call the inside, and its opposite theoutside. Fixed in this plate in suitable positions from its center, andprojecting perpendicularly on both sides are pins (c) on which, cams (d)are adjusted to operate the cut off valves (e). As these cams and theirattachments are alike, a description of one will be sufiicient. Thecircular or front edge (f) of said cam, which communicates motion to thevalve, is concentric to the pin on which the cam turns for adjustment,and is always in position to open the valve uniformly and at the righttime; while the nearly straight or back edge (s) of said cam whichgoverns the closing of the cut o valve, changes its position as requiredto cut oft1 variably. This cam is placed on the inside of the plate, andturns on the end of the pin projection from that side. A piece (it)somewhat similar in form to the cam, is placed on the outside of theplate, and turns on the end of the pin projecting from that side; it hasa long hub for increased bearng on the pin, and is united with the camon the inside by strong studs (i) passing through an opening in theplate, so that in eect, the two are as one piece turning on the samepin. The adjustment of the cam for cutting o variably is effected ashereafter described by a rod acting on a pin fixed on the said outsidepiece. On the back edge of said cam, which governs the closing of thecut ofin valve, I

No. 15,025, dated June 3, 1856.

use an adjustable sliding arrester (j) grooved on or otherwise suitablyattached for the purpose of arresting the motion of the valve and itsgear, just after closing, in such manner as to prevent ar andunnecessary wear of the parts; this arrester is connected at its innerend with one arm of the toggle joint, (is), the other arm of said jointbeing connected with the inner end of the cam, and the joint movingagainst the curved recess (Z) in the plate-said joint being held to thecurved face of said recess by an adjustable coiled spring and presserarm (m) fixed in the back part of the outer and of the cam, and pressingagainst the outer point of the sliding arrester, so that as the camturns upon its pin to vary the cut off the arrester slides out or in onthe back edge of the cam to adjust itself in position for easing off themotion of the valve and its gear as aforesaid.

On the same side of the plate with the cam, is fixed an inclined plane(n) suitably sloped to give the sliding cam roll (o) an inward lateralmovement as it leaves the back edge of the cam, and even with the top ofthis plane is fixed a thin steel sheet (p) which extends over the cams,and covers all that portion of the plate not required by the actingsurfaces of the cams and planes-so that the sliding roll, when the camhas left it, passes on and bears its rounded end (g) against the steelsheet, until the cam returns to the position required to open the cutoff valve, when the roll passes off from the steel sheet, over a slightextension of its edge and is thrown outward by an internal spring to itsposition to be again acted upon by the cam. Said sliding roll is made toslide and turn in a long bearing (o) in the end of one part of thecurved double arm (s), and on an internal pin (t) fixed in the end ofthe other part of said arm, said sliding roll having a suitable interiorspring acting against the interior end of said pin. The two parts ofsaid arm are firmly united by the shaft (u) to which they are fastenedand with which they swing, and also by the connecting pin (o) whichthrough the rod (fw) and the crank and valve stem imparts motion to thecut off and exhaust valve united. I use strong adjustable coiled springs(a) which act through the lever (l) and the rod (2) upon t-heconnect-ing pin uniting the two parts of said curved arm, and force therolls against the acting edges of the cams by which the valves receivemotions due to the forms of the cams ;-the force of the springs closingthe steam and opening the exhaust ports.

On the same main pin with the thick plate I place an exhaust cam whichreceives an oscillating motion from another eccentric or its vequivalent properly adn justed. This cam being double, and so shaped onits working edges and adjusted on said main pin as to work the exhaustvalve in proper time, acts upon a roll (4) that turns on the pin fixedin the end of one part of said double arm, and opposite said slidingroll. Said double arm consisting of two parts firmly united asdescribed, is a rigid device, carrying said two rolls to be acted onalternately by the steam, and exhaust cams. rlhe circular or holdingedge of the exhaust cam, is depressed or drawn in a little toward itsaxis, from the point where it meets the nearby straight edge, so thatits roll shall not come in contact with it, until the arrester on thecut off cam has performed its ofhce on the sliding roll in easing offthe motion of the cutoff valve and its gear.

)When the steam and exhaust valves are not united in one and operated asabove described, but the exhaust valve is separate and operatedindependently, the sliding roll is not allowed to pass on and bear itsend against the steel sheet, after receiving an inward lateral movementfrom the inclined. plane, but is held against the force of said coiledsprings (e) by a rim or cam (5) having the same form and adjustment asthe circular edge of said exhaust cam, and applied to said steel sheet,and against the force of said interior spring, by a double catch (6)suitably fastened upon a pin passing through the two parts of the doublearm, and is released by a pin (7) projecting from the plate and liftingthe catch in time for the roll to be thrown out in position to be actedupon by the cam as before described.

The adjustment of the cams for cutting off steam variably, is effectedby a screw turned either by hand or a regulator. The screw (8) is placedat a suitable distance from the outside of the thick plate on a lineparallel to its face and radiating from its axis; and turns in bearings(9) at each end, held between two guides (10) placed parallel to theaxis of the screw, and supported from the plate; the out-side guideterminates .in a ring (11) about the center of the plate and forms a tieto the pins on which the cut off cams move.

There is a sliding carrier (12) movable along the guides which carries acylindrical nut (13) adapted to receive the screw; the nut passesthrough the carrier and can,

turn in it, but is kept from moving endwise when brought up at eitherend against the stop collars of the screw, by a flange (14) at each end;inside the carrier are friction clamps (15) made adjustable by right andleft hand screws (16) and surrounding coil springs (17) arranged so asto bind the nut with pressure friction, and keep it from turning, withinany desirable limit of power; one of said screws having on its end asmall binding nut (18) and being turned by the movement of the other foradjust-ment, through the intermediate gear (19); on two sides of thecarrier are projecting ears (20) through which pins (21) pass and serve,by connecting rods (22) to communicate the motion of the carrier to thepins fixed in the outside pieces of the cut off cams for theiradjustment by the movement of the governor, or other regulator.

It will be observed that all attachments to the thick plate must partakeof its oscillating motion; while the regulator shaft (24) can only turnin stationary bearings; in order therefore to maintain a connectionbetween the screw and the regulator shaft, I place on the end of the pinthat supports the plate a bevel gear (25) free to turn either way, andmeshing with it and lfastened on the end of the screw is a similar gear(26), and in like manner, on the end of the regulator shaft is anothersimilar gear (27) so that the plate and its at-A tachments including thescrew oscillate about its center without affecting the regulator shaftany further than to impart to it a slight oscillation about its own axiswhich is prevented from continuing throughout its length, by making itin two parts, and forming a connect-ion between said parts by a coupling(28) withvclutches having suiiicient space between them to allow theoscillation of one part without the other.

Power applied to turn the regulator or hand shaft is transmitted throughthe gears to the screw, which acting in the nut moves the carrier uponthe guides until it reaches the end of the screw, when if the power becontinued in the same direction, the nutv will turn with the screw,overcoming the friction of the clamps.

The arrangement of the aforesaid strong coiled springs is the same foreach valve, as follows; a semicylindrical box (29) is attached by oneend to the engine frame, and in the center of each end a bearing isprovided for a shaft (30) which occupies the center Vof the box; on themiddle of the shaft said lever (1) is fastened to impart the power ofthe springs as before described; also on the shaft near each end betweenthe.

lever and the bearings, are placed ratchet wheels (31) free to turn inone direction on the shaft, but prevented from returning by the pawlswhich lare attached to the box, and catch in their teeth; the springs,one coiled from right to left, the other from left to right, occupy thespaces between, and are attached to the lever and the ratchet wheels,and are brought to the required tension by t-urning said wheels. A coveris neatly fitted to the box inclosing all parts except the lever, andhaving the external appearance of a simple cylinder. vWeights may beused instead of springs when more convenient.

l/Vhile my invent-ion admits the application of any kind of governorcommonly applied to regulate steam engine, l prefer to use the oneemployed to regulate the speed of water wheels, and known as the clutchgear iiy ball governor, in which a variation of speed will cause a shaftto turn to the right or left as required. I am thus en# abled to cut offthe steam variably in adjustment with the work of the engine, and bydispensing with the throttle valve, to work the steam upon the piston atnearly its full pressure in the boiler; and to simplify the valves innumber and operation and effect a saving in fuel.

All the figures are drawn on a quarter scale except Figs. 5, 8, 9, whichare drawn on a half scale to exhibit more distinctly the arrester andits parts and the sliding nut carrier and its parts. The scale may bevaried as required.

I claim l. The oscillating plate with its attachments, carrying theadjustable cut off cams acting with their sliding rolls for cutting offthe steam variably, substantially as described.

2. The self adjusting arrester and its part-s acting on the closing edgeof the adjustable cut oif cam for easing off the motion of the cut offvalve and its gear, substantially as described.l

3. The adjusted arrangement in combination, of the cut olf and exhaustcams, to work the cut olf and exhaust valves united, substantially asdescribed.

4. The double arm with its sliding and other roll, acting alternately onthe cut ofl, and exhaust cams substantially as described.

5. The gear joint connection between the regulator shaft and theadjusting screw, for working them together while one is fixed and theother oscillates, substantially as described.

6. The sliding carrier with its attachments and friction held nut, foradjusting the variable cut off cams on the oscillating plate, by theregulator, substantially as described.

7. The arrangement of the adjust-able coil springs in combination withtheir shaft and lever for forcing the rolls to the cams substantially asdescribed.

OTIS TUFTS.

Vitnesses:

W. H. Hicks, J. GILEs.

